Abstract:

A method for small-charge blasting, and a rock drilling unit used therein.
By means of a rock drilling machine of the rock drilling unit, a drill
hole is first drilled into material to be excavated, after which one or
more cartridges comprising a propellant charge are fed through a drilling
tool onto the bottom of the drill hole. The drilling unit comprises a
cartridge feed station, which is separate from the rock drilling machine
and from which the cartridges may be fed into a longitudinal channel in
the drilling tool.

Claims:

1: A method for small-charge blasting, the method comprising:performing
the blasting by a rock drilling unit comprising at least a feed beam, a
feed apparatus, a rock drilling machine and a drilling tool,drilling a
drill hole into material to be excavated with the rock drilling
machine,keeping the rock drilling machine in the direction of the drilled
hole after the drilling,feeding, after the drilling, at least one
cartridge comprising a propellant charge into the drill hole along at
least one channel in the drilling tool,feeding the cartridge from a
cartridge feed station into the channel of the drilling tool,sealing the
drill hole,igniting the cartridge, whereby a great gas pressure is
produced in the drill hole, causing cracking in the material to be
excavated,and feeding the cartridge into the channel of the drilling tool
from the cartridge feed station separate from the rock drilling machine.

2: A rock drilling unit for small-charge blasting, the drilling unit
comprising:a feed beam,a rock drilling machine,a feed apparatus, by which
the rock drilling machine is movable on the feed beam in the feed
direction and in the return direction,a drilling tool, which is connected
to the rock drilling machine and comprises at least one longitudinal
channel, anda cartridge feed station, by which a cartridge comprising a
propellant charge may be fed to the drilling tool and along its channel
into a drill hole,and the cartridge feed station is a unit separate from
the rock drilling machine.

3: A drilling unit as claimed in claim 2, whereinthe separate cartridge
feed station is arranged on the feed beam on the front side of the rock
drilling machine.

4: A drilling unit as claimed in claim 2, whereinthe rock drilling machine
and the cartridge feed station are arranged on the feed beam on the same
carriage.

5: A drilling unit as claimed in claim 2, whereinthe rock drilling machine
is arranged on the feed beam on a first carriage and the cartridge feed
station is arranged on the feed beam on a second carriage.

6: A drilling unit as claimed in claims 2, whereinthe rock drilling
machine is provided with an extended shank, which extends to the separate
feed station arranged on the front side of the rock drilling machine, and
at least the part of the shank on the side of the drilling tool comprises
a longitudinal channel,and the extended shank comprises at least one feed
opening for feeding cartridges from the cartridge feed station to the
channel of the shank and further to the channel of the drilling tool
connected to the shank.

7: A drilling unit as claimed in claim 2, whereinthe drilling tool
connected to the shank of the rock drilling machine comprises at least
one feed opening at the cartridge feed station for feeding cartridges
from the cartridge feed station to the channel of the drilling tool.

Description:

BACKGROUND OF THE INVENTION

[0001]The invention relates to a method for small-charge blasting, the
method comprising drilling with a rock drilling machine a drill hole into
a material to be excavated and feeding, after the drilling, at least one
cartridge comprising a propellant charge to the drill hole by means of a
drilling unit. After this, the drill hole is sealed before the cartridge
is ignited. The ignition of a small charge applies a great gas pressure
in the borehole, causing fracturing of the material to be excavated.

[0002]The invention further relates to a rock drilling unit for
small-charge blasting. The drilling unit comprises a feed beam, a rock
drilling machine and a drilling tool, which is connected to the rock
drilling machine and comprises a channel for feeding a cartridge along
the channel into a drill hole. The cartridge is fed to the channel in the
drilling tool by means of a feed station.

[0003]The field of the invention is defined in greater detail in the
preambles of the independent claims.

[0004]In small-charge blasting, a cartridge comprising a propellant charge
or a similar small charge is arranged in a drill hole. When the cartridge
is ignited, a great gas pressure is produced in the drill hole. A great
pressure in the drill hole causes controlled cracking in the material to
be excavated. Compared to conventional explosion blasting, small-charge
blasting provides the advantage that the rock drilling rig need not be
transferred away from the drilling site for ignition after the drilling,
and thus blasting may be carried out continuously. Furthermore,
small-charge blasting does not produce big stress waves, whereby the part
of the rock that is not to be broken, stays intact and does not require
support. Small-charge blasting is also safer and produces less dust.

[0005]U.S. Pat. No. 5,308,149 discloses a drilling unit comprising a rock
drilling machine and a feed apparatus for cartridges, which may be
indexed on a feed beam. First, a drill hole is drilled by the rock
drilling machine, and then the cartridge feed apparatus is indexed at the
drill hole for feeding cartridges into the drill hole. The cartridge feed
apparatus comprises a massive stemming bar, by which the cartridge is
pushed onto the bottom of the drill hole and by which bar the bottom of
the drill hole is also sealed. WO 2006/099 637 discloses an alternative
arrangement for small-charge blasting. It does not require a separate
cartridge feed apparatus in addition to the rock drilling machine, but
the cartridges are fed from a feed station in the rock drilling machine
to a shank and further through the drill rods to a drill bit, from which
they are led to the bottom of the drill hole. A drawback of this solution
is that it requires the use of a custom-made rock drilling machine.

BRIEF DESCRIPTION OF THE INVENTION

[0006]It is an object of the present invention to provide a new and
improved method and drilling unit for small-charge blasting.

[0007]The method of the invention is characterized by feeding the
cartridge into a channel of a drilling tool from a cartridge feed station
separate from the rock drilling machine.

[0008]The drilling unit of the invention is characterized in that the
cartridge feed station is a unit separate from the rock drilling machine.

[0009]The idea of the invention is that the cartridge feed station is
arranged separate from the rock drilling machine, which makes it an
individual unit separate from the rock drilling machine.

[0010]The invention provides an advantage that a quite normal rock
drilling machine may be used in the drilling, because the feed station is
an independent separate unit. In this case, the critical component, i.e.
the rock drilling machine, need not be constructed anew, but any
available percussion rock drilling machine or rotary rock drilling
machine may be used. In addition, the construction of the separate feed
station may be selected freely according to the need. Furthermore, the
feed station may be an easily replaceable component. All in all, the
structure of the equipment is simpler, because the rock drilling machine
and the feed station are separate units.

[0011]The idea of an embodiment is that a separate cartridge feed station
is arranged on the front side of the rock drilling machine.

[0012]The idea of an embodiment is that the rock drilling machine and the
cartridge feed station are arranged on the feed beam on the same
carriage.

[0013]The idea of an embodiment is that the rock drilling machine is
arranged on the feed beam on a first carriage and the cartridge feed
station is arranged on the feed beam on a second carriage.

[0014]The idea of an embodiment is that the rock drilling machine is
provided with an extended shank, which extends to the separate feed
station arranged on the front side of the rock drilling machine. In
addition, at least the part of the shank on the side of the drilling tool
comprises a longitudinal channel. The extended shank further comprises at
least one feed opening for feeding cartridges from the cartridge feed
station to the channel of the shank and further to the channel of the
drilling tool connected to the shank.

[0015]The idea of an embodiment is that the drilling tool arranged at the
shank of the rock drilling machine comprises at least one feed opening at
the cartridge feed station for feeding cartridges from the cartridge feed
station to the channel of the drilling tool.

BRIEF DESCRIPTION OF THE FIGURES

[0016]Some embodiments of the invention are explained in greater detail in
the attached drawings, in which

[0017]FIG. 1 schematically shows a rock drilling rig, which is provided
with drilling units of the invention for small-charge blasting,

[0018]FIG. 2 schematically shows a top view of a situation where a
cartridge and sealing medium are fed through a drilling tool into a drill
hole,

[0019]FIG. 3 schematically shows a side view of a rock drilling unit of
the invention, wherein a cartridge is fed from a cartridge feed station
situated on the front side of a rock drilling machine on its own carriage
to an extended shank and further by means of pressurized water along a
channel in the tool further to a drill hole, and

[0020]FIG. 4 schematically shows a side view of a second rock drilling
unit of the invention, wherein a cartridge is fed from a cartridge feed
station, which is situated on the front side of a rock drilling machine
and arranged on the same carriage, into a feed opening of the first
drilling tool connected to the rock drilling machine and further by means
of pressurized water along a channel in the drilling tool to a drill bit
and further onto the bottom a drill hole.

[0021]For the sake of clarity, some embodiments of the invention are shown
simplified in the figures. Like parts are denoted by the same reference
numerals in the figures.

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

[0022]A rock drilling rig 1 shown in FIG. 1 comprises a moving carrier 2,
three drilling booms 3a to 3c, and drilling units 4a to 4c on each
drilling boom. The drilling unit 4 comprises at least a feed beam 5, a
rock drilling machine 6, a feed apparatus 5a for moving the rock drilling
machine 6 on the feed beam in the feed direction A and in the return
direction B, and further a drilling tool 7 connected to the rock drilling
machine 6 and, in the front part of the feed beam 5, a front guide 8,
through which the drilling tool 7 is arranged. The drilling tool 7 may
comprise one or more drill rods 9 and a drill bit 10 at the outermost end
of the tool. Alternatively, the drilling tool 7 may be an integral rod,
the outermost end of which is provided with bits or the like. The rock
drilling machine 6 may be a percussion drilling machine comprising a
percussion device with which impact pulses are given to the drilling tool
and further transmitted by means of the tool to the rock or similar
material 11 to be excavated. The percussion rock drilling machine may
comprise a rotating device for turning the drilling tool about its
longitudinal axis. Alternatively, it may deal with a non-percussive rock
drilling machine, in which case the drilling is performed by the rotating
motion only. It is not relevant to the central idea of the invention,
which drilling technique is used for drilling a drill hole. Cartridges
used in small-charge blasting may be fed from a cartridge magazine 12 on
the carrier 2 along a feed channel 13 to a cartridge feed station 14 and
further along a channel 15 in the drill rod 9 into a drill hole 16, as
shown in FIG. 2. Alternatively, the cartridge magazine 12c may be located
at the drilling unit 4.

[0023]FIG. 2 illustrates the principle of small-charge blasting. A drill
hole 16 is drilled in the rock 17 conventionally by using the rock
drilling machine 6 and the tool 7 connected thereto. After the drilling
has been finished, the tool 7 may be pulled in the return direction B a
distance away from the bottom of the drill hole 16. The tool is, however,
held in the drill hole. After this, a cartridge P may be fed from the
cartridge magazine 12 or the like to the feed station 14 on the feed beam
5, the feed station being in connection with the longitudinal channel 15
in the tool 7. The cartridge P may be fed by means of a pressure medium,
such as pressurized water or air, or even a suitable pusher, such as a
cable, may be used. After one or more cartridges P have been fed to a
space between the drill bit 10 and the drill hole bottom, the drill hole
bottom may be sealed by feeding water from the channel 15. Sealing water
V fills in cracks in the drill hole, whereby the pressure caused by the
cartridge P is maintained better in the drill hole and the rock breaks
more easily. The sealing water V also serves as a medium transmitting the
pressure effect produced by the cartridge P to the rock. The tool 7 may
be held in the drill hole 16 for the time of ignition of the cartridge,
whereby the tool 7 serves as stemming for the mouth of the drill hole and
prevents the pressure produced by the cartridge P from escaping from the
drill hole 16.

[0024]After the cartridge P has been fed and the drill hole 16 sealed, the
cartridge P may be ignited by giving an ignition impulse by means of an
ignition apparatus 18 or the like. The cartridge P may comprise a
pressure-sensitive igniter, whereby it may be ignited by giving a
pressure impulse to filler water V around the cartridge by means of the
ignition apparatus 18. On the other hand, the ignition apparatus 18 may
give a mechanical impulse via the drilling tool 7 to the cartridge P
igniter, or the igniter may be ignited by means of electromagnetic waves
or impulses. The ignition apparatus 18 may be arranged in the drilling
unit 4. If electromagnetic waves are used for ignition, the ignition
apparatus 18 may be outside the drilling unit and the ignition may be
performed by remote control from the cabin of the rock drilling rig 1,
for instance.

[0025]FIG. 3 shows a greatly simplified view of a drilling unit 4, in
which, in the feed direction A, on the front side of the rock drilling
machine 6 there is arranged a cartridge feed station 14, which is an
independent physical unit separate from the rock drilling machine 6. The
rock drilling machine 6 may be arranged movably on the feed beam 5 by
means of a first carriage 19a, and the cartridge feed station 14, for its
part, may be arranged movably on the feed beam 5 by means of a second
carriage 19b. As a shank 20 for the rock drilling machine 6 with a basic
structure, a shank that is longer than usual may be arranged, the shank
extending to the feed station 14. In this case, a connection 21 between
the tool 7 and the shank 20 is on the front side of the feed station 14.
In the shank 20 there is at least at the feed station 14 an axial channel
22, which is in connection with the channel 15 in the tool 7. In
addition, the shank 20 comprises at least one cross-direction feed
opening 23, through which the channel 22 is in connection with a feed
chamber 24 of the feed station 14 and further with the feed channel 13 in
connection with the feed station 14. In this case, the cartridge P fed
from the feed channel 13 may be transferred, controlled by feed means 25
in the feed chamber 24 of the feed station 14, through a feed opening 23
into the channel 22 of the shank 20 and further along the channel 15 of
the tool 7 into the drill hole. The feeding means 25 may be an actuator
operated by a spring element 26, a pressure medium or the like,
transferring the cartridge P to the feed opening 23 in a direction
transverse to the drilling line. The feed station 14 may further comprise
sealing means 27, by which the shank 20 may be sealed in the feed station
14. In this way, the feeding of flush water supplied from the feed
channel 13 and/or the rock drilling machine 6, water used in the feeding
of cartridges P, sealing water V or a similar pressure medium is carried
out in a controlled manner. The feed station 14 may naturally be
constructed in a manner different from that shown in FIG. 3 by way of
example.

[0026]FIG. 4 shows a greatly simplified view of another rock drilling unit
4, which differs from that shown in FIG. 3 at least in that here the rock
drilling machine 6 and the feed station 14 are arranged on the same
carriage 19. Furthermore, a normal shank 20 is fixed to the rock drilling
machine 6 and the tool 7 is fixed to the extension of the shank. At the
section of the tool 7 end on the side of the rock drilling machine 6
there is at least one feed opening 23 extending from the outer surface of
the tool 7 to the channel 15, whereby a cartridge P may be fed through
it. The feed opening 23 is at the feed station 14. The tool 7 may
comprise one or more drill rods 28a, 28b, of which the first drill rod
28a closest to the rock drilling machine 6 is provided with the feed
opening 23.

[0027]FIG. 4 also shows by means of a broken line 29 a channel, which may
extend through a percussion element of the rock drilling machine 6, and
along which channel or along a pipe arranged through it water may be fed
to the shank 20 in order to feed cartridges P to the drill hole. Instead
of this pipe flushing, water may be fed into flushing channels in the
shank 20 through the feed channel 13 or from a channel 30 in connection
with the feed station 14. Driving force may also be supplied from the
channel 30 to a feed means 25 operated by a pressure medium.

[0028]It is to be noted that the feed station 14 need not necessarily be
located at a distance away from the rock drilling machine 6, as shown in
FIGS. 3 and 4, but the feed station 14 may be arranged against the front
part of the rock drilling machine 6. Yet another possibility is to
arrange the feed station on the back side of the rock drilling machine,
whereby the cartridges are fed along the channel 29 in accordance with
FIG. 4 through the rock drilling machine to the shank and further along
the channel in the tool into the drill hole.

[0029]In some cases, the features presented in this application may be
used as such, in spite of other features. On the other hand, the features
described in the present application may be combined to form different
combinations, if necessary.

[0030]The drawings and the related description are only intended to
illustrate the idea of the invention. In its details, the invention may
vary within the scope of the claims.